Patent GB-817758-A (GB)
Title: Improvements in or relating to safety interlocking systems
Inventor: GEORGE ERIC JAMES
IPC: G05G5/08
Filed: 1954-12-06
Abstract: 817,758. Locks; releasable fastenings. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Jan. 20, 1956 [Dec. 6, 1954], No. 35283/54. Class 44 A safety interlocking system comprises at least one locking device, the or each locking device including a locking member, at least one drive-transmitting means, the or each drive-transmitting means being associated with at least one of the locking devices and in operative engagement with the locking member of the or each locking device, a device for moving the or each drive-transmitting means between first and second positions and a master control for locking the or each drive-transmitting means against movement from the first position only, the or each locking device being operable to actuate its locking member to cause locking and release of its associated drivetransmitting means only when the latter is in the second position. As shown diagrammatically in Fig. 1, a locking device 1 for a door or panel of for example, a housing for electrical equipment, is connected by a flexible cable 2 to a means 4 for,moving the cable and to a master control 5 which includes a key-operated lock 6, the key of which is preferably used to operate a main power switch to a "power off" position and is trapped in the lock when the latter is operated to the unlocked position. The locking device 1 is mounted on the or each door jamb and is operated by a key mounted on the door. The locking device 1, comprises a wheel 14, Figs. 3 and 4, on a shaft 15 which is rotatably mounted in a two-part housing 10, 11 and is in operative engagement with the cable 2 which passes through the housing. A block 18 is slidably mounted on the shaft 15 and a pin 19 through the block 18 engages spiral slots 17 at that end of the shaft whereby the block may be engaged and disengaged from a diametral slot 20 in one face of the wheel 14. The shaft 15 is rotatable by means of a key member, Fig. 6, which is secured to the door or panel and comprises a shaft 26, rotatable by a knob 29 and carries lugs 27 which in the closed position of the door engage a slot 21 on the adjacent end of shaft 15 whereby the shaft may be rotated. The means 4 for moving the flexible cable comprises one or more wheels similar to wheel 14 corresponding to the number of cables to be operated, the wheels being rotated by a hand wheel 40. The master control 5, Fig. 7, comprises a housing 41 having a passage way for the cable 2 and an interconnecting link 45 and a slide 46, the latter being formed with a slot 51 for engagement by a bolt 52 of the lock 6 when the slide is in the position shown. In operation, the bolt is withdrawn from the slot 51 by the key which is then trapped in the lock. The hand wheel is then operated to move the cable 2 through the means 4 and the locking device thereby rotating the wheel 14 to bring the recess 20 into alignment with the block 18 which is thereafter moved into the recess by rotating the shaft 15 by means of the knob 29. This operation locks the wheel 14 against further rotation and permits the lugs 27 to be withdrawn from slot 21 and the door to be opened. The door is relocked by entering lugs 27 into the slot 21, rotating knob 29 to move the block 18 out of recess 20 and subsequently rotating hand wheel 40 to bring the slot 51 of the master control into alignment with bolt 52 which can then be shot to release the key from the lock.